<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <script>
      let num = 1
      function fn1() {
        let num = 8
        function fun1() {
          function fn() {
            console.log(num) // 打印多少为什么
          }
          fn()
          num = 6
          console.log(num) // 打印多少为什么
        }
        fun1()
      }
      fn1()
      //  8 和6 
    </script>
  </body>
</html>
